Electric controller



June 14, 1949. c, PERRY 2,473,256

ELECTRIC CONTROLLER Filed Oct. 24, 1944 I Fjgl.

Fig-3- I,

" an J Inventr-z Charles L. Perry,

His Attorneg.

Patented June, 1949 ELECTRIC CONTROLLER Charles L. Perry, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application October 24, 1944, Serial No. 560,159

Claims. (Cl. 200-12) My invention relates to electric controllers for energy translating devices or load devices, more particularly to electric switching and control means for starting and accelerating an electric motor for each direction of rotation, and has for its object a simple, reliable and inexpensive controller embodying current responsive protective means in a unitary structure, together with the reversing and accelerating means.

In carrying out my invention in one form, I provide a manually operated shaft on which is a plurality of cam operating means, together with forward and reverse starting switches and accelerating switches, and two circuit breaker switches which are closed by the cam means when the shaft is turned to an off position and which are held closed by means responsive to the current in the motor circuit when the shaft is turned to start and accelerate the motor. Thus, in the event of a current in the motor circuit greater than a predetermined maximum value, the electroresponsive means opens thecircuit breakers to deenergize the motor.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. 1 of which is an elevation view with the cover removed and partly in section of an electric controller embodying my invention; Fig. 2 is an enlarged plan view partly in section of one of the two current responsive circuit breakers; Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2 looking in the direction of the arrows; Fig, 4 is a plan view of an operating cam; Fig. 5 is a fragmentary view partly in section of the cam operating means for the starting and accelerating contactors; Fig. 6 is a plan View of an operating cam; while Fig. '1 is a. wiring diagram of an electric controller embodying my invention.

Referring to the drawing, in carrying out my invention in one form I provide a supporting framework and enclosure comprising a base portion I, a. top portion 2, and side supporting members 3 and 4 therefor. An operating shaft 5 is provided, on which is mounted a plurality of operating cams for the various switches in the controller, this shaft being mounted on suitable bearings (not shown) in the base I and top support 2. Moreover, the shaft 5 extends through the support 2 and has secured to it on its upper end an operating handle 6 provided with a releasable latch I cooperating with. a recess or groove in a projection 8 on the upper side of the plate 2. When the latch I is in this latching recess, as shown in Fig. 1, the handle and oper ating shaft 5 are in an off position. By depressing a button 9 on the end of the handle, the latch I is withdrawn from the recess to provide for turning movement of the handle and the operating shaft 5 in either direction, thereby to start the motor for the desired direction of rotation, and accelerate it to a running speed. Suitable star wheel and pawl means (not shown) are provided to position the operating shaft in its various operating positions.

An important feature of my invention is the incorporation in a unitary device of current responsive circuit breaker protective means for the motor along with the starting and accelerating means. As shown, I provide two switches or circuit breakers I0 and II' at the top for giving overcurrent and undervoltage protection for the motor. The next four switches I2, I3, I4, and I5 are starting switches for forward or reverse rotation of the motor, while the remaining five switches I6, IT, I8, I9, and 20 short-circuit a starting resistor in steps to accelerate the motor.

In Fig. 2, I have shown the details of construction of one of the two circuit breakers Ill. The switches I2-2Il inclusive have the same construction, with the exception that they have different cam operating means and do not have the current responsive opening means. Referring to Fig. 2, the movable contact 20a. is mounted on a switch arm 2I to cooperate with a stationary contact 25. Switch arm or member 2|, in turn, is mounted on a pivot 22 secured to a base or supporting member 23 made of electrically insulating material. secured to a support or base 24 extending between the supports I and 2 at the back of Fig. 1, although not shown in Fig. 1. Secured also to the base 24 is a supporting bracket 240. made of electrically insulating material on which is mounted th stationary contact 25, the blowout coil 26, and the arc chute or are extinguisher 21 made of electrically insulating material.

Also mounted on the base 24 is a holding coil 28 which, as shown in Fig. 3, is mounted on the center leg of a three-legged magnet core 29, the

This support 23 is, in turn,

poles of which extend across the two circuit breakers I and II. Thus, as shown in Fig. 3, the switch arm 2| is, in fact, made in two parts 2| and 2m consisting ofparallel metallic straps having their upper ends joined together, at which point is secured the movable contact 200.. The second switch or circuit breaker H is provided with a switch arm having the straps 3| and 3la mounted on a pivot 32, the two switches being separated by a plate of electrically insulating material 32a. These two switches in and I I are operated simultaneously by the two cams 33 and 34 mounted on the shaft and engaging respectively rollers 35 and 36 carried by the switch arms 2| and 3|. Also carried on the switch arms 2|, Zia and 3|, 3la are armature supports 31 and 31a carrying a bar armature 38 which engages the legs of a magnet 29 so that when the coil 28 is energized the circuit breakers are held by the coil in their closed circuit positions.

The barrierplate 320. made of electrically insulating material electrically separates the two circuit breakers Ill and II and actually forms the direct support for the blowout coil 26 and the arc chute 21, the barrier plate being part of the bracket 24a.

The are chute 21 is provided with a recess for the contacts a and and with a narrow aperture 39 into which the arc is forced for extinguishment. This movement of the arc into the aperture 39 is accelerated by the blowout coil 26 which is electrically connected between a terminal 40 and the movable contact 20a. A magnetic pole piece 4| is provided on one side of each of the arc extinguishers and is secured to the arc extinguishers. It extends to the right, as seen in Fig. 2, across one end of the blowout coil. Two such pole pieces are used for each arc chute of the circuit breaker, the lower one of the breaker Ii serving also as the upper pole piece of the switch 12. The pole pieces for the lower switches serve for both the switches above and below them.

As previously stated, the various switches I 0-20 inclusive are identical in construction, except for the shape of the cams and the electroresponsive holding means, and they are secured to the supporting bar 24 in closely spaced relation, as indicated in Fig. 1. The operating cams on the shaft 5 are constructed differently and arranged to give the desired sequence of operations. The cams 33 and 3:3, as seen in Figs. 2 and 3, are circular except for a projection 65 on each which, when it engages its roller 35 or 36, moves its switch arm to its closed circuit position. For each of the next four switches l2-i5i inclusive, a cam, as shown in Fig. 4, is provided consisting of a circular plate 44 having a groove on one side in which extends the roller on the contact arm. This construction is shown in Fig. 5, in which the roller 45 carried on one of the two straps 46 forming the switch arm lies in a groove 41 in the cam M. This groove consists of an arcuate portion 41a relatively close to the center of the shaft 5 and a second contactor closing arcuate portion 41b which is farther away from the center of the shaft 5. The object of the groove is to provide for positive opening, as well as closing, of the contact arms.

It will be observed that the cam 44 for the switches i2-l5 inclusive providesfor the opening of the switches throughout a substantially onehalf revolution of the groove portion 41a and the closing of the switches throughout the other portion 47b. This is to provide for the selective closing of two of the switches for the desired direction of rotation of the motor and the maintenance of these switches closed until the final running position is reached. At the same time, the two switches for the opposite direction of rotation are maintained in their open circuit positions by the portions 41a of each of their cams.

For each of the accelerating contactors Iii-20 inclusive, a cam is provided, as shown in Fig. 6. This cam has a groove or slot in one face having two relatively short switch closed portions 48a and 481) which are joined by arcuate portions nearer the center of the shaft 5, which portions hold the switches open. These closed portions 48a and 48b provide for closure of the particular switch at a particular position of the shaft 5 and the handle 6 for each direction of rotation.

Referring to Fig. 7, when the handle 6 is in the off, position, as shown, the cams 33 and 34 hold the switches 10 and II closed, the switches I 2-20 then being open. The motor is started by first closing a suitable manually operated line switch 50 which connects direct current supply mains to the stationary contacts of the switches l0 and II. The holding coil 28 is connected across the contact arms of the switches and is at this time energized so as to hold the circuit breakers I0 and II closed when the handle 6 is turned to close the motor circuit. It will be understood that when the handle 6 is turned from the off position in either direction, the operating projections 43 on the cams 33 and 34 disengage the circuit breakers so that they are held closed only by the coil 28.

Movement of the handle 6 in one direction closes, for example, the switches 12 and M for the closing of the motor circuit through the entire starting resistor 5| for the desired direction of rotation of the motor. When the handle is moved to the next step, the switch 20 is closed to short-circuit the lower portion of the resistor 5| and, as the handle is moved, the resistance is progressively short-circuited until it is completely short-circuited for the full running speed of the motor by the closure of the switch it. It will be understood that the cams for the switches iii-2U inclusive are mounted angularly on the shaft 5 to give the stated sequence operation of these contactors.

To give overload current response in the opening of the circuit breakers iii and. ii, I provide a coil 52 (Fig. 7) in the motor circuit which opposes or bucks the coil 28 so that upon the occurrence of a predetermined maximum current in the motor circuit and coil the coil 28 is weakened to such an extent that the circuit breakers it and ii are opened by their biasing springs thereby to deenergize the motor. I have found, however, that the coil 52 need not constitute a complete turn but may consist of only a small fraction of one turn. In my preferred form shown in Fig. 3, I provide for bucking the coil 28 two electrically insulated, electrically conducting bars 54 and 55 which are mounted on opposite sides of the holding coil 28 between the coil and the outside legs of the magnet core 29. Preferably, these bars 54 and 55 are included in the respective two sides or mains of the motor circuit.

In some cases, it may be desired to deenergize the motor in response to an overload by opening the circuit of the holding coil 28 instead of neutralizing its eifect. In such case, a suitable relay 56 (Fig. 1) connected in circuit with the motor is used. This relay may be adapted to give a time delay response to the overload as well as instantaneous response.

I contemplate that my controller can be used for the control of an alternating'current motor, the holding coil 28 then being energized through a rectifier, a suitable relay 56 being provided to open its circuit in response to an overload current.

The coil 28 is constructed to apply sufllcient magnetic force only to hold the circuit breakers i and l I closed after they have been closed manually by the cams 33 and 34. The coil 28 does not have suillcient force to close the circuit breakers. Therefore, if desired, the coil 28 may be connected directly across the line switch 50 so as to be energized at all times when the line switch is closed.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a direct current motor controller having a. plurality of motor starting and accelerating contacts and an operating member movable from an off position through a plurality of starting positions to a running position sequentially to actuate said contacts, a circuit breaker for connecting said controller to a source of direct current supply including a movable switch member biased to its open circuit position and a pair of cooperating switch contacts, means actuated by said operating member for moving said switch member to its closed circuit position when said operating member is moved to said oiT position,

magnetic means including a holding coil adapted to be connected across said supply source for holding said switch member in said closed circuit position when said operating member is moved away from said off position, and means respon sive to flow of excessive current through said switch contacts for rendering said magnetic means ineffective to hold said switch member, thereby to release said switch member for movement to its open circuit position in accordance with its bias.

2. In a direct current motor controller having forward and reverse motor starting contacts and a plurality of accelerating contacts and including an operating member movable in opposite directionsfrom an off position selectively to close said from an oil? position through a motor starting contacts and thereafter sequentially to actuate said accelerating contacts, a circuit breaker for connecting said controller to a source of direct current supply including a, movable switch member biased to its open circuit position and a pair of cooperating switch contacts, means actuated by said operating member for moving said switch member to its closed circuit position when said operating member is moved to said off position,-magnetic means including a holding coil adapted to be connected across said supply source for holding said switclr'member in said circuit closing position when said operating member is moved away from said off position in either direction, and means responsive to flow of excessive current through said switch contacts for rendering said magnetic means ineffective to hold said switch member, thereby to release said switch member for movement to I 6 its open circuit position in accordance with its bias.

3. In a direct current motor controller haping a plurality of motor starting and accelerating contacts and an operating member movable from an off position through a plurality of start: ing positions to a running position sequentially to actuate said contacts, a circuit breaker for connecting said controller to a source of direct current supply including a movable switch member biased to its open circuit position, means actuated by said operating member for moving said switch member to its closed circuit position when said operating member is moved toisaid ofl'position, magnetic means including a holding coil adapted to be connected across said supply source for holding said switch member in said closed circuit position when said operating member is moved away from said off position, and a bucking coil adapted to be connected in series circuit relation between said supply source and said motor and operable in response to flow of excessive current through said motor to neutralize the effect of said holding coil, thereby to release said switch member for movement to its open circuit position in accordance with its bias.

4. In a direct current motor controller hav ing a plurality of motor starting and accelerating contacts and an operating member movable plurality of starting positions to a running position sequentially to actuate said contacts, a circuit breaker for connecting said controller to a source of direct current supply including a switch member biased to its open circuit position and a pairv of cooperating switch contacts, means actuated by said operating member for moving said switch memher to its closed circuit position when said operating member is moved to said off position, magnetic means including a holding coil adapted to be connected across said supply source to hold said switch member in said closed circuit position when said operating member is moved away from said ofi position, and relay means responsive to flow of excessive current through said switch contacts for disabling said holding coil, thereby to release said switch member for movement to its .open circuit position in accordance with its bias.

5. In a direct current motor controller having forward and reverse motor starting contacts and a plurality of accelerating contacts and including an operating shaft rotatable in opposite directions from an off position selectably to close said motor starting contacts and thereafter sequentially to actuate said accelerating contacts, a circuit breaker for connecting said controller to a source of direct current supply including a movable switch member biased to its open circuit position and a pair of cooperating switch contacts, cam means actuated by said operating shaft for moving said switch memberto its closed circuit position when said operating shaft is moved to said off position, magnetic means including a holding coil adapted to be connected across said supply source for holding said switch member in said circuit closing position when said operating shaft is moved away from said off position in either direction, and means including a coil adapted to be connected in series circuit relation between said supply source and said motor and responsiveto flow of excessive current through member for movement to its open circuit posi- Number tion in accordance with its bias. 861,771 1 CHARLES L. PERRY. 868,140 850,443 REFERENCES CITED 5 904 90 The following referemces are of record in the 999-578 file of this patent: 1,789,069

UNITED'STATES PATENTS Number Name Date 10 Number 614,472 Ihlder Nov. 22, 1898 171,845

Name Date Rucker Nov. 13, 1900 Cutter Feb. 12, 1901 Pedersen Apr. 16, 1907 Wieaand Nov. 24, 1908 De Mayo Aug. 1, 1911 Grove Jan. 13, 1931 FOREIGN PATENTS Country Date Switzerland Dec. 1, 1984 

